compound boost. turbo on ctsv, gt500, ford gt, terminator... keeping the blower
#62
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^ The devil is in the details lol. As is obvious by the 89hp gain (12% increase) with the turbos only in that Hellion video, you don't really get the best of both worlds. You get a compromise, at best. You can do as I did and open the blower bypass once the turbo hits a preset boost level. This is a TVS 1900 and S475, sequential boost:
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1052.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1048.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1051.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1058.jpg)
It worked really well
I'd never run a traditional compound on a gas engine. This method of a blower/turbo combo will do everything you need and more.
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1052.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1048.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1051.jpg)
![](http://i271.photobucket.com/albums/jj129/anasasisxenophontis/IMG_1058.jpg)
It worked really well
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#63
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http://www.yellowbullet.com/forum/sh...light=compound
This thread has a huge amount of information. You have to weed out the misinformation that some people throw in though. A few of the guys in this thread have compound turbo setups with pictures and lot of details and results from different turbos on their setups. It's a really good read, but it'll take a while to read it all! lol
This thread has a huge amount of information. You have to weed out the misinformation that some people throw in though. A few of the guys in this thread have compound turbo setups with pictures and lot of details and results from different turbos on their setups. It's a really good read, but it'll take a while to read it all! lol
#64
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http://www.yellowbullet.com/forum/sh...light=compound
This thread has a huge amount of information. You have to weed out the misinformation that some people throw in though. A few of the guys in this thread have compound turbo setups with pictures and lot of details and results from different turbos on their setups. It's a really good read, but it'll take a while to read it all! lol
This thread has a huge amount of information. You have to weed out the misinformation that some people throw in though. A few of the guys in this thread have compound turbo setups with pictures and lot of details and results from different turbos on their setups. It's a really good read, but it'll take a while to read it all! lol
#65
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^ The devil is in the details lol. As is obvious by the 89hp gain (12% increase) with the turbos only in that Hellion video, you don't really get the best of both worlds. You get a compromise, at best. You can do as I did and open the blower bypass once the turbo hits a preset boost level. This is a TVS 1900 and S475, sequential boost
It worked really well
I'd never run a traditional compound on a gas engine. This method of a blower/turbo combo will do everything you need and more.
It worked really well
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
from what i am learning from this thread and the links on this thread the way you did it does not appear to be the only way to go or even the best way to go.
i question the compromise aspect of the compound set up. i think with a proper set up it really can be the best of both worlds and maybe even better than both worlds in some ways.
#67
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The video had enough information to show the power loss from running the blower in the mix lol... One simple modification and the power is gained right back. What you gain in cleaning up the air charge with the PD blower, you lose from the parasitic loss of the blower. The comparison isn't even close.
#68
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Whoa ton of misinformation above. Makes my head hurt. I’ll give it a shot…
All a turbo does is multiply atmospheric pressure.
You are dealing with pressure ratios and absolute pressure on compound setups. Yes, a compound setup will “multiply” aka compound the air resulting in higher manifold pressures dividing the work between the two turbo chargers at a specific ratio.
For example…
Lets say we have a typical single turbo diesel rig maxed out at say 40psi on the boost gauge. Take that 40psi and add 14.7 to it to get your absolute pressure at sea level. Total pressure would be 54.7psi absolute. Take that 54.7 / 14.7 and you get a 3.72 pressure ratio multiplier. So we will say that at a 3.72PR this turbo is maxed out.
If we were to add another larger turbo to this setup (sized properly and compounded) at a 2.2 pressure ratio the following would happen.
The large turbocharger is running at lower low boost and multiplies its 14.7psi inlet pressure by 2.2 times and sends out to the second (smaller) charger at 32.3psi absolute.
Now the small turbocharger will receive 32.3psi absolute (17.6lbs on the boost gauge) at its inlet and multiply that 32.3 by 3.72 just as it did before, but now the pressure output will be 120.16psi. The small turbo will still be spinning at the same speed it was maxed out at previously, but the manifold pressures more than double!
All a turbo does is multiply atmospheric pressure.
You are dealing with pressure ratios and absolute pressure on compound setups. Yes, a compound setup will “multiply” aka compound the air resulting in higher manifold pressures dividing the work between the two turbo chargers at a specific ratio.
For example…
Lets say we have a typical single turbo diesel rig maxed out at say 40psi on the boost gauge. Take that 40psi and add 14.7 to it to get your absolute pressure at sea level. Total pressure would be 54.7psi absolute. Take that 54.7 / 14.7 and you get a 3.72 pressure ratio multiplier. So we will say that at a 3.72PR this turbo is maxed out.
If we were to add another larger turbo to this setup (sized properly and compounded) at a 2.2 pressure ratio the following would happen.
The large turbocharger is running at lower low boost and multiplies its 14.7psi inlet pressure by 2.2 times and sends out to the second (smaller) charger at 32.3psi absolute.
Now the small turbocharger will receive 32.3psi absolute (17.6lbs on the boost gauge) at its inlet and multiply that 32.3 by 3.72 just as it did before, but now the pressure output will be 120.16psi. The small turbo will still be spinning at the same speed it was maxed out at previously, but the manifold pressures more than double!
As hard as this little MP112 pulls on the bottom end, I think a 88 or 90mm primary would come up on boost hard by 3000rpm and move double the air mass into the supercharger by the time you got to 4000-4500rpm. You'd have major torque from the supercharger at low rpm, and twice the air mass on top. With good cylinder heads, it seems like a win win.
#69
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The video had enough information to show the power loss from running the blower in the mix lol... One simple modification and the power is gained right back. What you gain in cleaning up the air charge with the PD blower, you lose from the parasitic loss of the blower. The comparison isn't even close.
yes i can see that top end power was gained when the blower was pulled off, graphing boost would add a lot to the value of this test. what you continue to ignore is that they are using too small of turbos to work ideally with the compound set up. i contend that with proper sized turbos the top end loss would be limited to only what the belt draws and might be made up by having a exhaust/intake pressure ratio of less than one. there is a ton of good info in that link above.
let me do the math on that gt500 set up and try and explain it to you for this particular set up.
stock boost on a gt500 appears to be around 9psi. looking at the chart above that means the turbos will need to be sprung at only 5psi. (5/14.7)+1= 1.34 pressure ratio is all those turbos will be at to make 17psi total.
next part is airflow. just a guess but for 700rwhp i would say 40+lbs of air each. now look where on the compressor map you land at 1.34 pressure ratio and 40+lbs of air with a 61mm turbo.
![](http://www.rbracing-rsr.com/turbo/TurboMaps/t61.gif)
compare that to a pair of large turbos where the turbine will be much larger(less back pressure) and the eff of the compressor will be much higher(less heat) and things are likely to improve.
the point is whatever turbos are going to work great without the blower are going to be too small with the blower even if your max hp goal does not change. i do not know how much real world effect there will be between running your turbos at 60% eff compared to 78% eff and how much a larger turbine housing is going to do. i suppose the next logical step to do if we are playing with the numbers is calculate the temp difference and what that would do to the hp. that would account for the eff loss of the too small turbo but not the reduced back pressure.
edit: i just did the math on just the added heat. i am not 100% sure on the math that i did but what i came up with when comparing a 55% eff comp for just the turbo compared to putting a turbo that is at 78% you gain about 30deg in temp and loose about 30hp. if that is the case then the hp diff at the very top shifts from 800vs711 to 800vs741. now lower the back pressure a little and likely gain more. once again without over laying the boost on those 2 runs we are just guessing.
Last edited by parish8; 11-24-2013 at 04:56 PM.
#70
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I know the math, Jim. And I agree with what you're saying...the blower+engine combo looks like a much bigger engine to those turbos, which are too small, as you said. But negating all the detains in this specific application, a turbo is still a far more efficient use of energy. The return from a blower is unarguably lower than that from a turbo. So it makes sense to use the blower to give you what you want (instant throttle response) and let the turbos take over once the blower has done its job. I posit that, given a setup that is optimized for a turbo, the engine will make more power and have a much lower BSFC with the blower running sequentially rather than compounded. This stands regardless of the turbo size, either running these turbos in the hellion kit, or larger ones... The net effect of not running in compound will be the same: more usable power.
#71
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soooo what did we decide here??????????? I have a customer with a 2300 maggy on his 6.2 ls3 that we were going to do a twin turbo build on and now hes asking if we can keep the blower and just add the turbos so its still got gangster low end instant TQ but more HP up top...? its a street car not a drag car and built more to have fun around town than anything soooo??
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#72
I need a gauge for that
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I talked to a couple guys that have done this back in the 80s and 90s and a problem they kept running into was eating the thrust bearings on the roots blowers. Something to keep in mind anyway.
As far as sizing, size the turbos for the CFM of the blower, not the engine. So if its a 6.2L and runs a 7lb pulley on the blower, size the turbos for a [6.2*(7+14.7)/14.7))=9.15L engine.
As far as sizing, size the turbos for the CFM of the blower, not the engine. So if its a 6.2L and runs a 7lb pulley on the blower, size the turbos for a [6.2*(7+14.7)/14.7))=9.15L engine.
#73
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I talked to a couple guys that have done this back in the 80s and 90s and a problem they kept running into was eating the thrust bearings on the roots blowers. Something to keep in mind anyway.
As far as sizing, size the turbos for the CFM of the blower, not the engine. So if its a 6.2L and runs a 7lb pulley on the blower, size the turbos for a [6.2*(7+14.7)/14.7))=9.15L engine.
As far as sizing, size the turbos for the CFM of the blower, not the engine. So if its a 6.2L and runs a 7lb pulley on the blower, size the turbos for a [6.2*(7+14.7)/14.7))=9.15L engine.
i hope to do this some day. 6.2 lsa with the stock blower and stock pulleys and a pair of 76's. if i ever decide to ditch the blower the 76's would be easy to sell.
#74
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#75
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I still think it comes down to what you are trying to achieve. If you are drag racing a car why the hell do you give a **** about the low end response of the engine? All you need to focus on is power around and above the stall point and maximizing that.
For road race you are probably only talking about 50% of the RPM range. If you are at any lower RPM than that and your in the wrong gear.
So once again what are you trying to achieve? For gut wrenching bottom end why not just push 20psi through a SC alone? if you want massive peak power than you aren't worried about the bottom end so ditch the SC and let the turbos do there work. Plus you can then use a decent intake manifold and get the advantages from that.
For a street car, Just match the turbos to the power you want to make in the RPM range you want to make! Simples.![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
I have seen 1.3ltr motorbike engines pushing 500bhp with little to no lag when used in a road race style car (Dax kit car). The turbo was a ex 1980s F1 unit and not using the latest technology (a Garrett TR30R would be even better!) and still response was great because the turbo matched the characteristics of the engine and what the person wanted to achieve.
Chris.
For road race you are probably only talking about 50% of the RPM range. If you are at any lower RPM than that and your in the wrong gear.
So once again what are you trying to achieve? For gut wrenching bottom end why not just push 20psi through a SC alone? if you want massive peak power than you aren't worried about the bottom end so ditch the SC and let the turbos do there work. Plus you can then use a decent intake manifold and get the advantages from that.
For a street car, Just match the turbos to the power you want to make in the RPM range you want to make! Simples.
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
I have seen 1.3ltr motorbike engines pushing 500bhp with little to no lag when used in a road race style car (Dax kit car). The turbo was a ex 1980s F1 unit and not using the latest technology (a Garrett TR30R would be even better!) and still response was great because the turbo matched the characteristics of the engine and what the person wanted to achieve.
Chris.
#77
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I still think it comes down to what you are trying to achieve. If you are drag racing a car why the hell do you give a **** about the low end response of the engine? All you need to focus on is power around and above the stall point and maximizing that.
For road race you are probably only talking about 50% of the RPM range. If you are at any lower RPM than that and your in the wrong gear.
So once again what are you trying to achieve? For gut wrenching bottom end why not just push 20psi through a SC alone? if you want massive peak power than you aren't worried about the bottom end so ditch the SC and let the turbos do there work. Plus you can then use a decent intake manifold and get the advantages from that.
For a street car, Just match the turbos to the power you want to make in the RPM range you want to make! Simples.![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
I have seen 1.3ltr motorbike engines pushing 500bhp with little to no lag when used in a road race style car (Dax kit car). The turbo was a ex 1980s F1 unit and not using the latest technology (a Garrett TR30R would be even better!) and still response was great because the turbo matched the characteristics of the engine and what the person wanted to achieve.
Chris.
For road race you are probably only talking about 50% of the RPM range. If you are at any lower RPM than that and your in the wrong gear.
So once again what are you trying to achieve? For gut wrenching bottom end why not just push 20psi through a SC alone? if you want massive peak power than you aren't worried about the bottom end so ditch the SC and let the turbos do there work. Plus you can then use a decent intake manifold and get the advantages from that.
For a street car, Just match the turbos to the power you want to make in the RPM range you want to make! Simples.
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
I have seen 1.3ltr motorbike engines pushing 500bhp with little to no lag when used in a road race style car (Dax kit car). The turbo was a ex 1980s F1 unit and not using the latest technology (a Garrett TR30R would be even better!) and still response was great because the turbo matched the characteristics of the engine and what the person wanted to achieve.
Chris.
i am more interested in if i all ready have a blower because it came on the car what are the advantages and disadvantages of keeping it or removing it when adding turbos.
i am hoping that using both will allow the car to rip off the line with a stock converter AND make obscene top end power while driving like stock.
#78
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i really dont disagree with anything you said and i would not pay for both a blower and turbo.
i am more interested in if i all ready have a blower because it came on the car what are the advantages and disadvantages of keeping it or removing it when adding turbos.
i am hoping that using both will allow the car to rip off the line with a stock converter AND make obscene top end power while driving like stock.
i am more interested in if i all ready have a blower because it came on the car what are the advantages and disadvantages of keeping it or removing it when adding turbos.
i am hoping that using both will allow the car to rip off the line with a stock converter AND make obscene top end power while driving like stock.
#79
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I am sorry, but I think it's gay to do this. The only compounding one should do, if you have a blower car, is add nitrous. Lots of it, if you are not makeing the power you want. Which will also cool the blower charge. Blower and nitrous is a pair made in heaven. And this is a way to approach turbo efficacy and turbo torque with a blower car.
If you have turbos, a small shot would help off the line, like a 50 shot. I am not a fan of using nitrous on a turbo car though. Because you can leave fully boosted. But I can see how lag would effect roll races. If that is your worry, a 50 shot would help before the coolers.
I am sorry, but it is just gay to me, and a waste of money, even if you got it to work well. Gay...
If you have turbos, a small shot would help off the line, like a 50 shot. I am not a fan of using nitrous on a turbo car though. Because you can leave fully boosted. But I can see how lag would effect roll races. If that is your worry, a 50 shot would help before the coolers.
I am sorry, but it is just gay to me, and a waste of money, even if you got it to work well. Gay...